fix(handlers): compile error in approvals.go + broken test mock in p1102

- approvals.go: err was already declared at line 37 (ctxJSON, err := json.Marshal).
  Reusing with = instead of := to fix "no new variables on left side of :=".
- approvals_test.go: TestApprovals_Create_NilContextFallsBackToEmptyJSON mock
  expected 6 args for an INSERT with 5 columns. Remove spurious
  sqlmock.AnyArg() that caused "expected 6, got 5 arguments" at runtime.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

workspace-server/internal/handlers/approvals.go

@@ -34,13 +34,19 @@ func (h *ApprovalsHandler) Create(c *gin.Context) {
 		return
 	}
 
-	ctxJSON, _ := json.Marshal(body.Context)
-	if ctxJSON == nil {
+	ctxJSON, err := json.Marshal(body.Context)
+	if err != nil {
+		log.Printf("Create approval: json.Marshal(context) error: %v", err)
+		ctxJSON = []byte("{}")
+	} else if len(ctxJSON) == 0 {
+		// json.Marshal returns []byte{} (empty slice, not nil) on error;
+		// guard against it defensively even though map[string]interface{}
+		// cannot fail in practice — defensive in depth.
 		ctxJSON = []byte("{}")
 	}
 
 	var approvalID string
-	err := db.DB.QueryRowContext(ctx, `
+	err = db.DB.QueryRowContext(ctx, `
 		INSERT INTO approval_requests (workspace_id, task_id, action, reason, context)
 		VALUES ($1, $2, $3, $4, $5::jsonb)
 		RETURNING id

workspace-server/internal/handlers/approvals_test.go

@@ -328,3 +328,35 @@ func TestApprovals_Decide_MissingDecision(t *testing.T) {
 		t.Errorf("expected 400, got %d", w.Code)
 	}
 }
+
+func TestApprovals_Create_NilContextFallsBackToEmptyJSON(t *testing.T) {
+	mock := setupTestDB(t)
+	setupTestRedis(t)
+	broadcaster := newTestBroadcaster()
+	handler := NewApprovalsHandler(broadcaster)
+
+	mock.ExpectQuery("INSERT INTO approval_requests").
+		WithArgs("ws-1", "task-0", "approve", "none", sqlmock.AnyArg()).
+		WillReturnRows(sqlmock.NewRows([]string{"id"}).AddRow("appr-nil"))
+
+	mock.ExpectExec("INSERT INTO structure_events").
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	mock.ExpectQuery("SELECT parent_id FROM workspaces WHERE id").
+		WithArgs("ws-1").
+		WillReturnRows(sqlmock.NewRows([]string{"parent_id"}).AddRow(nil))
+
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+	c.Params = gin.Params{{Key: "id", Value: "ws-1"}}
+	// context is nil (zero value of map[string]interface{})
+	body := `{"action":"approve","reason":"none","task_id":"task-0","context":null}`
+	c.Request = httptest.NewRequest("POST", "/", bytes.NewBufferString(body))
+	c.Request.Header.Set("Content-Type", "application/json")
+
+	handler.Create(c)
+
+	if w.Code != http.StatusCreated {
+		t.Errorf("expected 201, got %d: %s", w.Code, w.Body.String())
+	}
+}